1. Field of the Invention
The present invention relates generally to articles and methods for delivering powder compositions to an enclosed environment and, more particularly, to a shoe insole structure having a plurality of reservoirs containing an active ingredient powder, where the powder can be released to the interior of a shoe by walking on the insole.
Foot odor and infection are common problems caused by microbial growth in the enclosed environment of the shoe. Moisture resulting from foot perspiration provides an ideal growth environment for both bacteria and fungus, causing odor and athlete's foot, respectively.
The inhibition of such microbial growth has been a long sought goal of the shoe industry, and numerous approaches have been proposed and tried. Commonly, activated charcoal is incorporated into a shoe insole in order to absorb odor and moisture. Although partly effective in controlling odor, the degree of moisture absorption is not sufficient to inhibit microbial growth in most cases. Thus, the odor continues to be produced and athlete's foot and other infections can occur. Moreover, the ability of the activated charcoal to absorb odor is quite limited and the effectiveness of the insole is usually short-lived.
Antimicrobial agents have also been incorporated within a shoe insole with varying degrees of success. Usually, however, the anti-microbial agents are either released too rapidly to provide for long-term effectiveness or entrapped to securely within the insole to provide for sufficient activity. The ideal system for the extended delivery of anti-microbial and deodorant agents from a shoe insole has yet to be found.
Thus, it is desirable to provide improved articles and methods for delivering deodorants and antimicrobial compositions to the shoe environment during use. The delivery of such compositions should last over numerous wearings of the shoes and should provide a generally uniform distribution of the composition throughout the entire region of the shoe as the wearer walks thereon. The articles and methods should be capable of delivering a wide variety of compositions, including anti-bacterial agents and fragrances for odor control and anti-fungal compositions for the control of athletes foot and other infections. Desirably, the articles should be sealable so that they can be stored for extended periods without substantial loss of activity prior to use.
2. Description of the Relevant Art
U.S. Pat. No. 2,560,120, discloses an insole having vertical passages which communicate with a single reservoir of a moisture absorbing agent which may be a powder. The powder is located only beneath the instep and is never released through the passages. Instead, air recirculates through the passages and the moisture absorbent material. U.S. Patent Nos. 4,187,622 and 2,911,973, each disclose the release of a foot powder through a mesh or porous layer in an insole. The insole structures, however, both include common reservoirs which will allow shifting of the foot powder away from the areas of maximum foot pressure. Thus, the foot powder will not be distributed as evenly as would be desirable. U.S. Patent Nos. 4,517,308 and 4,257,176 each disclose the incorporation of an encapsulated deodorant or perfume in an insole structure. Other structures for deodorizing footwear are described in U.S. Patent Nos. 4,533,351; 4,461,099; 2,061,911; and WO 86/02559.